Accurate analyses of samples, regardless of the source, begins with the method for collecting the sample. Core samples of soils and sludges must be reliable, accurate, and reproducible in determination of the depth at which a sample was taken and must minimize contamination by soils and sludges at different depths. Numerous devices have been reported.
U.S. Pat. No. 3,978,932 to Mielke discloses a core sampler for soils characterized by a resilient retaining ring beneath a liner. U.S. Pat. No. 5,831,185 to Maxwell et al. discloses a pneumatically driven core sample having a trap door to retain the sample.
U.S. Pat. No. 4,376,392 to Beitel discloses a pneumatic sludge sampler. U.S. Pat. No. 5,474,141 to Hart discloses a chisel shaped core sampler with a trap door collection system. U.S. Pat. No. 5,492,021 to Bourgeoise et al. discloses a core sampler for hard surfaces based upon a hole saw.
U.S. Pat. No. 5,494,119 discloses a pneumatic core sampler with a split spoon collector. U.S. Pat. No. 4,096,749 to Stewart discloses a double-walled core sampler for testing wet concrete. U.S. Pat. No. RE 37,066 to Casey et al. is directed to a soil sampler with multiple removable liners for collection at different depths.
Common commercial samplers are available from vendors such as Enviroquip, Fisher Scientific, Kahl Scientific Instrument Corp., AMS Inc., and Advanced Concepts and Designs, Inc.
Core samplers for soils require a driving system, often pneumatic. Samplers for silts, sludge, other semi-plastic materials and granular or comminuted material may be hand operated. Accuracy of depth of the collected sample becomes critical, especially with rivers, lakes and ponds, storage tanks, and other soft materials which have been serially loaded with (different) contaminants and/or have been mixed before analytical processing. Improved, easier to operate, accurate sludge samplers always are in demand.